Vibrator type multiple-shot blasting unit



1950 F. c. GIBSON ETAL VIBRATOR TYPE MULTIPLE-SHOT BLASTING un'rr Filed July 15, 1947 l l I I o I I I I I I a I I FRANK C. G/B50N OWN fEEDE/P/CK [V 5/? INVENTORS Patented May 9,

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VIBRATOR TYPE MULTIPLE-SHOT BLASTING UNIT Frank C. Gibson, Broughton, Pa., and Frederick W. Brown, 'Los Angeles, Calif.

Application July is; is", Serial No. 261,125 10 Claims: (01. 171-97) (Granted under the an of March s, .1883, as amended April 30,1928; 370 0. G. 757) without the payment to us of any royalty thereon It is an object of this invention to provide a blasting unit capable of detonating simultaneously a plurality of blasts connected in series.

It is an object of this invention to provide a blasting unit that is safe, reliable and may be used in underground mining operations where gas ignition hazards exist.

It is also an object of this invention to provide a blasting unit which is portable, durable, relatively inexpensive and simple to operate.

It is a further object of this invention to provide a blasting unit, the primary source of energy of which is a small battery such as a miner's cap lamp battery.

The foregoing and other objects will become apparent from the following specification taken.

inconnection with the drawing which shows a schematic view of a blasting unit embodying the principles of this invention.

Input terminals in and I l are provided to which may be attached a small battery l2 such as a miners cap lamp battery. Terminal I is connected to blade it of double-pole, double-throw switch l5. Terminal I I is grounded. Switch l5 also includes blade I6. I Blades i6 and I6 are ganged for simultaneous operation and are biased in a normal position by spring I8. Blade It in its normal position engages a contact not otherwise connected in the circuit. In the operated condition of switch l5 blade [4 engages contact i'l connected to the mid point of primary of transformer 2|.

Transformer 2 lis interconnected with vibrator to provide a power supply for the blasting unit.

I Vibrator 25 comprises a grounded vibrating reed 2B which is caused to vibrate by magnet coil 21. Vibrator 25 also includes contacts 29, 30, SI and 52, contacts 29 and SI being on one side of said 2 a reed 26 and contacts 30 and 32 being on theother side thereof. Vibrating reed 26 at one extreme oi its vibrating cycle engages contacts 29 and 3| and at the other extreme of said cycle engages contacts 30 and 32. The end terminals of primary 20 are connected to contacts 29 and 30. The secondary 23 of transformer 2| has a center tap which is connected to ground through voltage dividing resistor 35. The end terminals of secondary 23 are connected to contacts 3! and 32. A resistor 36 and a condenser 31 are connected in series across the end terminals of secondary 28. Blade" l8 of switch, l5 in the normal position of switch I5 is connected through a resistor 38 to ground. In the operated position of switch It blade 16 is connected to an adjustable tap on resistor 85. Blade is is connected to a contact 39 of switch 60. Switch a0 is similar to switch it being a double-pole, double-throw switch including blades ti and 62 which are ganged for simultaneous operation and which are biased to a normal position by spring 65. In the normal position of switch 60 blade M engages contact 39 and is thus connected to blade it of switch l5. In the operated position of switch 40 blade M engages contact $5 which is connected to contact 46 of switch 40. Blade 62 in the unoperated condition of switch Ml engages contact 61. In the operated condition of switch as blade 42 engages contact at. Condenser i9 and gaseous glow lamp 50 are connected in parallel and across blade ti and contact M of switch to. Contact 51 is connected to ground. Blade 42 of switch 80 is connected to output terminal 5 l The other output terminal 52 is connected to ground.

A plurality of explosive charges or blasts 58 and 55 each including electrical detonating means 58 and 51, respectively, may be connected to output terminals 5! and 52 with the detonating means 55 and 51 connected in series.

In the operation of the device describedabove a battery I! is connected to input terminals It and II and a series of electrical detonators such as 55 and 51 associated with explosive charges 55 and 55, respectively, are connected in series between output terminals 5! and 52. It will be understood that a greater number of explosive charges may be placed in series with the output terminals 5!, 52 than are shown in the drawing.

When switch I 5 is in its normal unoperated position, blade M of switch l5 engages an otherwise unconnected contact so that battery I2 is eflectively isolated from the blasting unit circuit. When switch 40 is in its normal or unoperated position condenser 49 is discharged through blade of reed 26 with contact 29 shorts coil 21 cutting down the attraction thereof for reed 26 and allowing reed 26 to swing back past its mid position to engage contacts 30 and 32. Immediately on the breaking of the engagement between contact 29 and reed 26 coil 21 begins to build up an attraction for reed 26 causing this reed to eventually swing back to engage again contacts 26 and 3|. This cycle is continuously repeated, the natural period of reed 26 being designed for the frequency of vibration desired.

It will be seen that as reed 26 engages first contact 29 and then contact 33 that an alternating flux will be set up in primary 2!] of transformer 2| to induce an alternating voltage in secondary 23. This alternating voltage will be rectified as reed 26 alternately engages contacts 3| and 32 to provide a relatively high direct current voltage across resistor 35. Bufiing condenser 31 is connected in series with resistor 36 across the end terminals of secondary 22 to give the proper wave form for long vibrator life. Resistor 36 is used to protect the transformer in case of failure of condenser 31.

With switch IS in its operated position the adjustable tap along resistor 35 picks up a voltage therefrom which is applied through blade 16 of switch 15 and through contact 39 and blade 4| of switch 40 to condenser 49 which is charged thereby. As the condenser 49 becomes charged its potential rises and when the condenser is substantially fully charged a sufiicient potential is applied across glow tube 50 to cause it to glow.

A resistor 48 in series with glow lamp 50 properly limits the current through the glow lamp. The lighting of lamp 50 shows condenser 49 to be adequately charged and in good condition and indicates generally that the unit is functioning properly.

To fire the explosive charges, switch 46 is operated. Operation of switch 46 disconnects blade 42 from contact 41, thus removing the short across output terminals 51 and 52, and connects condenser 49 through blade 4!, contacts 45 and 46, and blade 42 of switch 40 to the electrical detonators 56 and 51 of explosive charges 54 and 55, respectively to detonate these explose charges, the circuit being completed through the ground connected to contact 41 and terminal 52. The firing cycle can be stopped at any time during charging by allowing switch 15 to return to its unoperated position which discharges condenser 49 through resistor 38.

Vibrator 25 is completely enclosed by a shielding can 33. Any sparks produced at the vibrator contacts during operation of the vibrator are eI-' fectively isolated by shielding can 33 from the atmosphere in which the unit is operated. Can 33 also protects the vibrator during handling. To prevent operation of the unitby accident, switches I and 40 should be recessed into the case. It is preferable that the entire blasting unit be enclosed in a waterproof container and sealed to preventunauthorized tampering.

It will be seen that this invention provides a portable, durable, relatively inexpensive multiple shot blasting unit which is simple to operate, requires minimum maintenance and has no periodical component replacement. The cap lamp battery required as a primary source of energy is used by underground mine workers in nearly all mines. This battery is almost universally available and it is common practice for it to be recharged daily. The cap lamp battery is therefore a. reliable and convenient source of energy for a miner's blasting unit. The capacity of condenser 49 as well as the potential picked up by the adjustable tap or resistor 35 and applied to condenser 46 is selected to produce a combination which will provide adequate energy to fire the electric blasting caps and still limit the time duration of the impulse to meet safety requirements.

In practice the complete firing cycle requires approximately three seconds and requires only the initial operation of switch l5 until the glow lamp 50 glows and then operation of switch 44 to fire the charges. The blasting unit will operate successfully from a 4-volt cap lamp battery and may safely be used in a, gaseous atmosphere to fire ten detonators in series. The unit herein described when slightly modified can be used to initiate or more electric blasting caps in series in blasting operations where conformance to rigid safety regulations is not required.

It wi l be understood that the embodiment of the invention described above is exemplary only and that many modifications within the scope of the appended claims will occur to those skilled in the art.

What is claimed is:

1. In combination a first switch connected be tween an input and a means for multiply Voltage, said first switch connecting said input to said voltage multiplying means only when said first switch is operated, a second switch connected to said voltage multiplying means, a condenser and an output, said second switch in its normal position acting to connect said condenser to said voltage multiplying means and said second switch in its operated condition acting to connect said condenser to said output.

2. The combination of claim 1, in which the voltage multiplying means includes a vibrator interconnected with a transformer.

3. The combination of claim 1, in which the voltage multiplying means comprises a vibrator interconnected with a transformer having a primary and a secondary, whereby the vibrator interrupts the voltage applied to said primary and rectifies the voltage derived from said secondary.

4. The combination of claim 1, in which a gasfilled glowtube is connected across said condenser to indicate the charge therein.

5. The combination of claim 1, in which said first and second switches are interconnected so that when saidfirst and second switches are in their unoperated position said condenser is discharged.

6. The combination of claim 1, in which a battery is connected to said input.

'7. The combination of claim 1, in which a battery is connected to said input and an electrical detonating device is connected to said output.

8. The combination of claim 1, in which a battery is connected to said input and a plurality of electrical detonating devices are connected in series across said output.

4 9. The combination of claim 1, in which said second switch in its noal position also acts to short-circuit said output.

10. In combination, an input connected to a.

first and second switch means to operate in synchronous and ganged relation, a condenser, a glow tube in series with a resistor connected across said condenser, a third switch means connected in its normal position to said second switch means, and in its operated position to a fourth switch means when the fourth switch sition to one plate of said condenser, said third switch means being always connected to the other plate of said condenser, said fourth switch means being always connected to an output, and means to cause said third and fourth switch means to operate in synchronous and ganged position.

FRANK C. GIBSON.

ERICK W. BRQWN.

R EBENCES m The following references'are of record in the tile 0! this patent:

UNITED STATES PATENTS Number Name Date 941,852 Broadwater Nov. 30, 1909 1,133,183 Reinke Mar. 23, 1915 1,70%,131 Johnson Mar. 5, 1929 1,795,972 Ruhlemann Mar. 10, 1931 1,920,150 Rockwell July 25, 1933 2,331,058 Stick, Jr Oct. 5, 1943 FOREIGN PATENTS Number Country Date Germany Dec. 13, 1930 

